Flying machine



June 8 1926. 1,588,141

- ROHRBACH FLYING MACHINE Filed March 24, 1924 4 Sheets-Sheet 1 I June 8 1926. v

. A. RQHRBACH FLYING MACHINE Filed March 24, 19 24 4 Sheet S-Sheet 2 A. ROHRBACH FLYING MACHINE June 8,1926. 1,588,141

File d March 24, 1924 4 Sheets-Sheet 5 June 8 1926.

A ROHRBACH FLYING MACHINE Filed March 24, 1924 4 Sheets-Sheet 4 Patented June 8, 1926.

UNITED STATES ADOLF ROHBBAGH, F QHARLOTTENBURG, GERMANY.

FLYING macnmn Application filed March 24, 1924, Serial No. 701,498, and hi Germany April 27. 1923.

\ It is well known that it is very diflicult'to build a flying machine. with propellers disposed on the opposite sides of the central plane of the machine so that it is able to con- 5 tinue its horizontal flight when one of its propellers has stopped. These difliculties result from two causes:

- 1. With many flying machines the poweravailable after one of the propellers has stopped, is smaller than the power required to maintain a level flight.

2. As soon as one propeller fails to work, the steering moment of therudder and the ailerons is not's'uificient to secure a straight flight. v

The aerodynamic knowledge acquired hitherto, resulting in a very small air resistance and light weight of an up-to-date aero engine permits the. building of flying machines with such a margin of power that they can safel continue their flight even after 50% of t eir power, i. e. e. g., one motor out of two, has failed to work.

Prior to my invention there has been no entirely satisfactory solution of the problem of compensating for the dissymmetry of the propulsion resulting from the failure of one propeller so as to,maint-ain. a reasonable amount of lateral and transverse stability and reserve steering moment. Various twin-engined flying machines al ready proved to be able to continue their straight flight after one of their propellers had been cut out, although this was accomplished nearly always with a reduced amount of loading. Besides, all such experiments were made in favour-able weather and calm air so that the flying machines were exposed to little disturbances, if any, by squalls. no special demand being made with regard to lateral and transverse stability and to reserve rudder power when flying on part of their propellers. It is a fact that none of the twin-engined flying machines of any type has proved in practical service to be capable to fly under any conditions on one motor only. Practically the rudder cannot be made so large and the hull so long that the effect of the rudder is sufiicient to enforce-with a suflicient reserve-a straight flight, when one of the plropellers lateral to the plane of symmetry, as stopped;

This is quite obvious, if a rudder together with its fin is imagined to form one single vertical surface. If such a surface advances against a s mmetrical air current, as is the case when oth air propellers are working, the air speed is considerably lower on the hollow side of this surface than on its convex side.

The symmetry of the air flow ahead of the fin'and rudder is disturbed as soon as one of the laterally arranged propellers stops, since in this case the slip stream on this side disappears whereas it remains the same as before on the other side and becomes still relatively stronger owing to the reduced flymg speed'.

From the foregoing it is clear that in such an asymmetrical flow the effect of the rudder can be only quite insignificant since the rudder has to be inclined towards that side on which the propellers are still working Owing to the slip stream the velocity of the air on this hollow'side of fin and rudder is now nearly as great as or even reater than on the other side, although accor ing to what was said before, just the opposite ought to be the case in order to produce a strong 0 steering effect of the rudder.

It is for these reasons that many special devices, e. g. special correcting surfaces which have been tried to increase the rudder efficiency with twin-engined machines, have u had little or no success.

By my invention I avoid these difficulties and I effect this by special arrangement of supporting frame and-tail unit structure embodying generally the feature of turning all on tail unit surfaces around an approximately vertical axis whereby the above explained slipstream effect upon the rudder and fin is substantially compensated for. Such tail unit includes a special construction 'and mounting of the various control surfaces together with a special disposition-- and arrangement of the actuatingmean's for effecting a thoroughly practical solution of the problem.

steering mechanism.

several embodimentsof 'my invention are enable the actuation of the rudder in any poshown, by way of example, on the accompanying drawings, wherein Fig. 1 shows in side elevation a steering and longitudinal control mechanism for a flying machine.

Fig. 2 is a plan view of Fig. 1. g

Fig. 3 is a diagrammatical illustration of a modified construction of tail unit.

'Fig. 4 shows a modified design of the mechanismillustrated in .Fig. 3. FFig. 5 is a section on line VIIVII,0f

gig. 6 shows a further modification of the For convenience in illustration I have illustrated in the drawings only'the rear part 1 of the main supporting frame or body extending rearwardly of the craft,the remainder of the craft, including the supportin planes and propellers on the opposite si es thereof being omitted for convenience in illustration. In the embodiment of Figs. l and 2 I'have illustrated the rear portion 1 .of the fuselage as divided into two parts 17 and 18, these parts beingpivotally connected together for relative adjustments in the horizontal plane, as described below. The part 17 carries the whole tail unit including the normally stationary vertical fin 3, the rudder 6. pivoted thereto, .the horizontal stablizer 8 and the elevator 9, the stabilizer 8- and the elevator 9 being mounted on the fin 3 at a substantial distance above the level of the fuselage, as indicated.

The rear end 17 of thehull 18 can be inclined against the hull to a certain extent. This is effected by means of an axle 19 and a lever 20 which is rigidly fixed tothe rear end '17, a nut 21 at the free end of said lever engaging a screw threaded spindle 22 so that by the rotation of this spindle which is produced by cables 23 and drum 24, the rear part 17 of the hull with tail planes is inclined against the symmetry plane of the flying machine. The horizontal tail planes 8 and 9 are, as described above-mounted on the fin 3 and at a point substantially above the level of the fuselage. I have indicated generally a mechanism for operating the elevator 9, ineluding the pivoted lever 10. and the connecting link 10' leading up to a lever connected with the elevator 9, suitable cables 11 omitted 'forconvenie'nce in illustration. The

. a'double sector 15 which is connected withrudder 6 is indicated as mounted for pivotal movement about the axis 7 above the fin 3 and the actuation thereof is efiected through the shaft 7' for operating and controlling the same and including the cable 16 indicated as passing through the pivotal axis 19, so as to bearings.

sition of the trailing part 17 of the fuselage. It will be noted that here the entire tailplane unit, comprising the rudder 6, the fin .3, and the horizontal tail-planes 8 and 9, is

arranged to swing on the vertical axis 19 to the desired position of adjustment.

In the modification described above, it is ditlicult to fix the fin with its vertical pivot tion inthe ibearings is transmitted to the fin which therefore will vibrate the more easily the shorter the distance between the two This inconvenience is avoided bythe construction represented in Fi s. 36.

' In the rear part of the hu 1 1 of the fiyin machine represented in Fig. 3 a so-eall kingpost 25 is used as support for the tail planes. This post carries the hinges for the fin,

at the upper part as step axle and at the lower part as ball or roller bearing 27. In the kingpost itself a hollow guide 28 is arranged which may simply consist of a tube or any other hollowsupport. Care has to be taken, however, that the control cables or rodsll for the rudders and elevator run exactly in,

guide 28 is avoided. The control cables 11 for the rudder run from the rudder bar in front of the pilots seat over a pulley 32' touching the central axis of the king post 25, through the guide 28, and over the upper pulley 33 to the lever of the rudder. v

The control cables for the elevator run over the pulleys 34 and are attached in a sleeve 35 of the guide 28; from this sleeve 35 they run over .1. reversing pulley 36 and a guide pulley 37 back to the stick in the pilots cab. 5

The tail planes can be turned to a certain extent around'the axle 19. A nut 39 is fixed to the front e'nd of the fin by means of a bolt 38, said nut being-screwed upon a spindle 40...

The pitch of the screw-spindle is so selected ment may of course be substituted for the nut and spindle. The spindle is turned or rotated from a coaxial pulley 41 over which the controLcables are guided from an operating lever (or wheel) near the pilots seat.

In the design of Fig. 4 the control cables are guided through the hull in order to re duce the air resistance. The mechanism is somewhat modified in order to make the king post 25 as small as possible. In this post only a plain tube is arranged, no pulley, sleeves or the like being mounted in the same. Thus the construction. is not only simplified but the cost of manufacture is reduced, the reliability of the mechanism being the same as in the above-described design. v

The rudder is operated in the same way as in the design of Fi 3. The control of the elevator, however, is simplified by guiding the control cables 16 overs, segment 42 for displacing or shifting the guide 43, 28. In this embodiment of my invention the tail-plane shifting and concurrent automatic locking device is constmcted and arranged as follows:

The whole tail plane unit, comprising the fin 3, the rudder 6 and the horizontal taillanes 8, 9, pivots round the king post 25 y the rotation of a crank 44, the pin 38 of which is mounted in the fin. The rotation of the crank ma be produced in various manners. Accor ing to the design of Fig. 4 it is rotated by means of a worm 45, operated by a cable running to the drivers cab,

'and a worm wheel 46.

Figs. 5 and 6 illustrate a form of carrying out my invention which, as compared with the above described embodiments, presents the advantages of a shorter hull combined with an enlarged fin. In this example the main axle 25 is arranged in advance of the fin 3. This main axle in the present in- I stance comprises the upper and lower pivotal bearings 471 and 47 and the tubular guide 28 engaging the lower pivot bearing 47. The

fin 3 is 1n turn provided withthe three hinged-ears 29, 29" and 56 which embrace the three parts 471, 28 and 47 of the axle 25. The guide 28 is mounted in the bearings 30 and 47 in such a. way as to be vertically adjustable and also to turn in said bearings. The cables for the rudder are arranged to pass centrally and longitudinally through this guide 28 and over the pulleys 32 and 33 to connect with the operating lever 48 of the rudder 6. .The control cables for the elevator act upon a segment 42 on the axle 49 of which a toothed sector 50 is keyed, said sector meshing with a circular rack 51 formed or mounted on and encircling the ide' piece 28. I

On'turning 51 h sector 50 by means of the controlcables 16 the guide 28 be raised or lowered, thereb lowering or raising the elevator 9 throug the intervention of the hinge stud 31 mounted on the guide 28 which is engaged by the forked part 311 on the,

lever arm 10 rigidly secured to and extending forwardly from the pivot 312 of the elevator.

The inclination of the taillane unit is governed and controlled by te pulley 52 on the axle of which a worm 54, gearing with the worm, wheel sector 55, is mounted.

This sector is preferably constructed and arranged as shown; that is to say, it is formed on the ear 56 ofthe fin- 3, which ear embraces the lower post or pivot bearing 47 forming part of the axle 25. These parts again constitute a shifting device for the tail-plane unit around its vertical axis which concurrently acts as an automatic locking device for any position to which said tailplaneunit may have been swung or shifted.

In this latter design the distance between the bearings is very great so that the pressures on the bearings are considerably smaller than with'bearings arranged. closely together.

The mechanism operates as follows When flying normally on all propellers the tail plane unit is in its normal position,

i. e. in the symmetry plane of the flying machine. If' one of the propellers is not working the pilot gives to the tail plane unit by means of the control cables such as inclination relatively to the symmetry plane ofthe is pivoted so that it may be swung around a substantially vertical axis, the pivot for such purpose constituting a vertical axle, as in Figs. 1 and 2, or a vertical king post, as in Figs. 3 to 6, or vertical bearings in which a vertical pillar i's'journaled, as in Figs. 1 and 2. 7

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is 1. In a flying machine of the character described, the combination with the hull of a tail-plane unit comprising a vertical fin with a "ertical rudder movably secured to the rear of the fin and a horizontal tail-plane and elevator. the vertical fin being pi'votally mounted to swing around a vertical axis at the rear of the hull, and means for swinging the tail-plane unit around said axis.

2. In a flying machine, a hull provided at Inn its rear with a vertical axle, -in combination with a fin =mountedonsa1d vertlcal axle, and

with a rear vertical king-post and a tailarudder hinged to the rear of the fin, whereby the fin and the rudder may be swung togcther with respect to the vertlcal plane of symmetry of the flying machine.

3. In'a flying machine, a hull provided with a rearvertical pivotal axle, and a tail plane unit adapted to swing on said axle, 1n combination with means for operating a movable part of said unit, said means being arranged substantially axially with respect to the pivotal axle. ,4. In a flying machine, a hull provided with a rear vertical king-post'and a tailplane unit pivotally engaging said klngpost, in combinationwith means for operating the elevator forming part of said unit, said means being arranged within and substantiallyvon the axis of said king-post.

5. In a flying machine, a hull prov1ded plane unit pivotally engaging said king-post, in combination with means for operating the rudder forming part of said unit, said means being arranged within said king-post and substantially on the axis of the same.

'6. In a flying machine, a hull provided with a rear vertical axle, and a'tail-plane unit pivotally engaging said axle, in comblnation with means comprising a cable for operating a movable part on said unlt, said cable passing through the axle in a substantially axial position.

7.'A tail unit for an aeroplane having propellers situated on opposite sides of the longitudinal center line t ereof mcludlng a vertical fin movable about a vertical axis,

a horizontal control element carried by and mounted upon said pivoted vertical fin and a rudder pivotally connected to the 'rear of said vertical fin for adjustments independently thereof.

8. A tail unit for an aeroplane having propellers situated on opposite sides of the longitudinal center line thereof including a fin which is pivotally mounted about an axis which is approximately vertical to the tail end of the fuselage, a vertical rudder hinged to said fin for adjustments independently thereof, a horizontal stabilizer and elevator carried by said adjustable fin and means for independently actuating the elevator, the

I so

rudder and the adjustable fin in any of the relative positions which they may occupy.

. 9. A tail unit for an aeroplane having propellers situated on opposite sides of the longitudinal center line thereof including a vertical fin which is pivotally mounted about an axis which is approximately vertical to the tail end of the fuselage, a "ertical rudder pivotally connected to said adjustable vertical fin anda horizontal control surface carried by said vertical fin at a point ele-. vated substantially above the level of the fuselage, together with means for lindepend- I ently controlling and actuating said 7 adjustable fin and said rudder in any relative positions which they may occupy.

10. A tail unit of the character set forth in claim 9 wherein the horizontal control surface includes a horizontal stabilizer and an elevator hinged to the rear thereof, together with means for controllin and manipulating said elevator in any of t 1e relative positions of the rudder and adjustable fin.

11. A tail unit for an aeroplane havingpropellers situated on the opposite sides of the longitudinal center line thereof, including a king-post rigidly carried adjacent the rear end of the fuselage, a vertical fin adjust-ably carried by said king-post for movements thereabout as a pivotal axis, a rudder pivotally carried by said fin, a longitudinal control surface also carried by said vertical fin-andmeans for independently actuating said vertical fin, said rudder and said lon i tudinal control surface in any of the relative positions which they may occupy.

12. A tail unit of the character set forth in claim 19 wherein the means for actuating the longitudinal control surface and the vertical rudder are disposed partly along the pivotal axis of the king-post.

: 13. A tail unit of the character set forth in claim 19 wherein the longitudinal control surface is actuated by adjusting devices disposed partly within the pivotal axis of the vetrical fin.

14. A tail unit of the character set forth in claim 19 in which the actuating devices of the vertical rudder are partly disposed within the ivotal axis of the vertical fin.

15. A tail unit of the character set forth in claim 19 wherein the king-post is disposed intermediate the forward and rearward edges of the vertical fin.

I 16. A tail unit of the character set forth in claim 19 wherein the vertical fin is pivotally carried at its forward edge by said kingpost and the latter includes a rigid nose part protruding upwardly from the fuselage to form the leading edge of the vertical fin.

17 A tail unit of the character set forth in claim 19 wherein the king-post is disposed intermediate the forward and rearward edges of the vertical fin and the actuating means for the fin engages the latter at one of said edges.

18. An aeroplane including an elongated rearwardly extending frame for supporting the tail unit, said frame being longitudinally divided at a point removed from its rear end with the two parts pivotally connected together for adjustments about a substantially vertical axis and a tail unit including horizontal and vertical control surfaces carried by the rearmost pivoted partof the body frame.

19. An airplane including a longitudinally extending supporting frame, a king-post carried by said supporting frame adjacent the rear end thereof, a vertical fin mounted for turning movements,about said king-post as an axis and having a pivotal connection c therewith at a point adjacent its uglier end, a rudder pivotally carried by said ,a 1ongitudinal control surface also carried by said fin and means for independently actuating said vertical fin, said rudder and said longi- 10 tudinal control surface in any of the relative positions which they may occupy.

In testimony whereof I hereunto affix my signature.

DR. ADQLF 'ROHRBACH. 

